1. Field of the Invention
This invention relates to a new endless power transmission belt construction and to a new cord for the load-carrying section of the belt construction as well as to a new method of making such an endless power transmission belt construction and a new method of making such a cord.
2. Prior Art Statement
It is known to provide a p-aramid fiber cord for use as a component in a power transmission belt construction or the like, the cord comprising three plies twisted together in one direction at a rate to approximately equal a first certain twist multiplier with each ply comprising two yarns of a plurality of p-aramid fiber filaments having a certain denier and being twisted together in a direction opposite to the one direction at a rate to approximately equal a second certain twist multiplier, each twist multiplier being equal to the quotient of the product of the turns per linear inch of twisted material multiplied by the square root of the product of the certain denier of the fiber filaments multiplied by the total number of the yarns being twisted at that time divided by seventy-three. For example, see the U.S. patent to Carlson et al, U.S. Pat. No. 4,083,260.
It is also known to form the cord for an endless power transmission belt construction from fiber filaments made of a p-aramid material sold under the trademark TECHNORA of the Teijin Corporation of Japan and sold in the United States by Teijin Shoji New York Inc. of New York, N.Y. For example, see the U.S. patent to Nakajima et al, U.S. Pat. No. 5,230,667.
It is one of the features of this invention to provide a new cord for an endless power transmission belt construction wherein the new cord has improved characteristics over a prior made cord formed of standard p-aramid fiber filaments.
In particular, the prior made cord comprises three plies twisted together in one direction at a rate to approximately equal a first certain twist multiplier with each ply comprising two yarns of a plurality of p-aramid fiber filaments having a certain denier and being twisted together in a direction opposite to the one direction at a rate to approximately equal a second certain twist multiplier, each twist multiplier being equal to the quotient of the product of the turns per linear inch of twisted material multiplied by the square root of the product of the certain denier of the fiber filaments multiplied by the total number of the yarns being twisted at that time divided by seventy-three, the yarns and the plies being twisted together so as to cause the longitudinal axes of the fiber filaments to be disposed generally perpendicular to the longitudinal direction of the cord with the certain denier being approximately 1500, the first certain twist multiplier being created by the three plies being twisted together at a rate of approximately 4.7 turns per linear inch of the cord, the second certain twist multiplier being the result of two yarns being twisted together at a rate of approximately 4.7 turns per linear inch of that resulting ply.
However, it was found according to the teachings of this invention that instead of utilizing standard p-aramid fiber filaments as previously set forth, a technical synergy results if the fiber filaments can be formed of a modified p-aramid comprising co-poly (paraphenylene/3,4' oxydiphenylene terephthalamide) with a balanced twist multiplier and having the yarns and the plies respectively twisted on a 2 for 1 twister means so as to cause the longitudinal axes of the fiber filaments to be disposed generally in the longitudinal direction of the cord and with the denier of each yarn being approximately 1500, the first certain twist multiplier being 3.7687 as the three plies are twisted together at a rate of approximately 2.9 turns per linear inch of the cord, the second twist multiplier being 3.6765 as the two yarns for each ply are twisted together at a rate of approximately 4.9 turns per linear inch of that ply.
It was found that the resulting cord of this invention has improved break characteristics over the prior known cord formed of the standard p-aramid fiber filaments as set forth hereinafter.
Thus, one embodiment of this invention comprises a p-aramid fiber cord for use as a component in a power transmission belt construction or the like, the cord comprising three plies twisted together in one direction at a rate to approximately equal a first certain twist multiplier with each ply comprising two yarns of a plurality of p-aramid fiber filaments having a certain denier and being twisted together in a direction opposite to the one direction at a rate to approximately equal a second certain twist multiplier, each twist multiplier being equal to the quotient of the product of the turns per linear inch of twisted material multiplied by the square root of the product of the certain denier of the fiber filaments multiplied by the total number of the yarns being twisted at that time divided by seventy-three, the yarns and the plies being respectively twisted on a 2 for 1 twister means so as to cause the longitudinal axes of the fiber filaments to be disposed generally in the longitudinal direction of the cord with the certain denier being approximately 1500, the first certain twist multiplier being 3.7687 as the three plies are twisted together at a rate of approximately 2.9 turns per linear inch of the cord, the second certain twist multiplier being 3.6765 as the two yarns for each ply are twisted together at a rate of approximately 4.9 turns per linear inch of that ply, the p-aramid comprising co-poly (paraphenylene/3,4' oxydiphenylene terephthalamide).
Accordingly, it is an object of this invention to provide a new cord for use as a component in a power transmission belt construction or the like, the cord of this invention having one or more of the novel features of this invention as set forth above or hereinafter shown or described.
Another object of this invention is to provide a new method of making such a cord, the method of this invention having one or more of the novel features of this invention as set forth above or hereinafter shown or described.
Another object of this invention is to provide a new power transmission belt construction utilizing such a cord, the belt construction of this invention having one or more of the novel features of this invention as set forth above or hereinafter shown or described.
Another object of this invention is to provide a new method of making such a belt construction, the method of this invention having one or more of the novel features of this invention as set forth above or hereinafter shown or described.
Other objects, uses and advantages of this invention are apparent from a reading of this description which proceeds with reference to the accompanying drawings forming a part thereof and wherein: